An important characteristic of an electronic package is its ability to transfer heat out of the integrated circuit (IC) chip in order to ensure its proper operation and reliability. A considerable amount of heat is generated by the internal and surface circuits including transistors, resistors, capacitors, and other electronic components of an integrated circuit (IC) device. Fine ball grid arrays (FBGA) have superior electrical performance and has gained in popularity in memory packaging. As semiconductor devices become more dense, heat generation has greatly increased, requiring package construction that will transfer heat out of the IC chip in order to ensure its proper operation and reliability. However, the smaller package outline of an FBGA reduces the surface area essential for thermal heat transfer.
Conventional approaches to addressing thermal issues is by extrinsically mounting a passive heat transfer device, or heat sink, to the surface of the die. For example, heat spreaders and extruded or pins fin type of heat sinks have been mounted on the active surface of a semiconductor die to absorb heat from the IC die and dissipate the heat by convection into the air. However, these extrinsic heat sink structures substantially increase the size and complexity of a semiconductor device, and do not address the problem of achieving enhanced microchip cooling in a simple, low-cost packaging arrangement. Applications in the area of hand-held and mobile products require space constraints in package height, thus eliminating the possibility of using extrinsic heat spreaders and heat sinks.
Conventional methods of increasing the number of copper substrate layers, using a thicker copper ground plane layer, or using a higher thermal conductivity mold compound can be effective for thermal enhancement of high pin count packages such as a plastic quad flat pack (PQFB) and plastic ball grid array (PBGA) configuration. However, these approaches provide negligible impact on an FBGA-BOC package due, at least in part, to the much thinner package structure and small surface area in the memory application.
Thus it would be desirable to improve FBGA thermal performance and package reliability while maintaining a thin die package profile.